A 16-YEAR-OLD has been arrested for murdering his mother with a dumbbell a day after he made an emotional TV plea to find her killer.

Brad George, 16, of Washington state, was arrested on Saturday a day after his mum, Georgina Latshaw, 37, was found dead in her bedroom.

The teenager had called 911 after he said he returned home from school to find the front door open and her car in the driveway which he said was unusual.

He didn’t go inside but immediately called 911 and police found Latshaw’s body.

After his arrest, George reportedly told police that he broke into Latshaw’s room while she was sleeping on Thursday night and waited until she was snoring before he bludgeoned her with a dumbbell. He went to school the next day.

He said he had stopped taking medications for a mood disorder on February 1 and started believing that Latshaw was poisoning him with bleach. George is a student at Overlake Speciality School for troubled children with special needs and has a history of violent outbursts and mental illness.

Latshaw had taken George in 10 years ago and had adopted him.

He was taken to a psychiatric hospital on Saturday where he was confronted about his role in the murder.

He reportedly became catatonic, pulling off a wooden arm from a chair and walking towards a nurse with his arm raised ready to strike her. Two security guards disarmed him. He is said to have admitted to the killing after this.

It isn’t the first time that he has had psychotic episodes. In 2010, he was admitted to hospital after having hallucinations that his mum was a short clown with blood in her mouth. Family members said George had threatened Latshaw at least once with a knife.

It was a different picture to the one seen on TV screens a day earlier when George appeared with his sisters to talk about their mum’s death.

“She has supported me my whole life. She always knew what was best for us. I don’t know who could have done this,” he said before his arrest. “This doesn’t feel real, this all feels fake.”

Police said they noticed holes in George’s story when they found a dumbbell in his room, bloodstained men’s clothing in the garbage and no signs of forced entry.

George is being held on $US500,000 bail and will be charged as an adult given the severity of the crime.